Automated implantation system for radioisotope seeds

ABSTRACT

An automated implantation system assists the implantation of low dose radioisotope seeds in a patient as part of a brachytherapy procedure. A Z-axis automated motion control system and an X-Y axis automated motion control system control a needle assembly. The X-Y axis automated motion control system positions an insertion axis of the needle assembly relative to the patient. The Z-axis automated motion control system selectively moves the needle assembly along the insertion axis to implant at least one radioisotope seed. This process is repeated for a plurality of locations on a base plane perpendicular to the insertion axis. Preferably, the radioisotope seeds are contained in a replaceable cartridge and the needle assembly is also replaceable.

RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 10/010,968, filed Nov. 13, 2001, entitled “AUTOMATEDIMPLANTATION SYSTEM FOR RADIOISOTOPE SEEDS,” which claims priority totwo provisional applications filed Nov. 10, 2000, the first of which isentitled “AUTOMATED IMPLANTATION SYSTEM FOR RADIOISOTOPE SEEDS,” U.S.Provisional Application No. 60/247,229, and the second of which isentitled “USER INTERFACE FOR AN AUTOMATED RADIOISOTOPE SYSTEM,” U.S.Provisional Application No. 60/247,482, and which is acontinuation-in-part of two co-pending applications that are commonlyassigned to the assignee of the present invention, the first of which isentitled “AUTOMATED RADIOISOTOPE SEED LOADER SYSTEM FOR IMPLANTNEEDLES,” U.S. application Ser. No. 09/587,624, filed Jun. 5, 2000, andthe second of which is entitled “RADIOISOTOPE SEED CARTRIDGE,” U.S.application Ser. No. 09/587,642, filed Jun. 5, 2000, the disclosures ofall of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to the field of medical devicesfor handling radioisotope materials. More specifically, the presentinvention relates to an automated implantation system for implanting lowdose radioisotope seeds in a patient as part of a brachytherapyprocedure.

BACKGROUND OF THE INVENTION

The use of radioisotopes for various medical procedures such asbrachytherapy and the like is well known. Such uses fall into twogeneral categories: (i) high dose radioisotopes which are temporarilypositioned in relation to a patient's body for a relatively short periodof time to effect the radiation treatment; and (ii) low doseradioisotopes which are permanently implanted in a patient's body withthe duration of the radiation treatment determined by the strength andhalf-life of the radioisotope being implanted.

High dose radioisotopes are typically implanted using a catheterarrangement and a device commonly known as an afterloader that advancesthe high dose radioisotope located on the end of a source wire throughthe catheter to the desired location. Low dose radioisotopes, on theother hand, are implanted using an array of implant needles with the lowdose radioisotopes being encapsulated in very small containers known asseeds that are manually loaded into a series of implant needles and thenejected to form a three-dimensional grid of radioisotopes in the patientthat corresponds to a dose plan as determined by the physician.

The goal of the low dose brachytherapy procedure is to position thisthree-dimensional grid of radioisotopes seeds in and around a targetcancerous tissue area. Each of the radioisotope seeds consists of aradioactive source such as Iodine (I-125) or Palladium (Pd-103) inside asmall tube-like titanium shell that is about the size of a grain ofrice. These types of low dose radioactive sources emit a very low energyradiation that is primarily absorbed by the tissue immediatelysurrounding the radioisotope seed. This constant low energy radiation istypically emitted by the radioisotope seeds for a period of up to sixmonths as a way to kill the cancer cells in the target area withouthaving to subject the patient to the discomfort and risks that oftenaccompany high dose radioisotope procedures.

One common brachytherapy procedure is the use of low dose radioisotopesto treat prostate cancer. Although brachytherapy procedures using lowdose radioisotopes can be applied to many different parts of the body,it is helpful to describe a particular treatment to gain a betterunderstanding of these treatments. In a typical prostate cancerprocedure, a predetermined number of seeds (between 1-6) are positionedwithin each of a series of implant needles (up to 40), with the seedsbeing spaced apart in each needle by small spacers. A small amount ofbone wax is positioned on the tip of the implant needles to prevent theseeds and spacers from falling out until they are implanted in thepatient.

The loaded implant needles are positioned at the appropriate locationfor insertion into the perineal area of the patient using a stand thathas an X-Y coordinate grid. Each needle is manually positioned in theappropriate chamber in the grid and is inserted into the patient. Anultrasound probe is used to assist the physician in guiding each of theneedles to the desired location. The seeds and spacers are deliveredfrom the tip of the implant needle using a stylet and hollow needlearrangement where the hollow needle is preferably retracted while thestylet remains in place. When completed, the implanted seeds form athree-dimensional grid of radioisotope sources that implements apredetermined dose plan for treating the prostate cancer in the patient.For a more detailed background of the procedures and equipment used inthis type of prostate cancer treatment, reference is made to U.S. Pat.No. 4,167,179.

There have been numerous developments in the design of equipment for usein low dose radioisotope procedures. U.S. Pat. Nos. 5,626,829,5,682,892, 5,868,757, 5,931,786, 5,957,935 and 5,961,527 describeimprovements in the stands and grids used to stabilize and guide themanual placement of needles during a low dose radioisotope procedure.U.S. Pat. Nos. 4,586,490 and 4,627,420 describe manually operatedimplanting devices that substitute for the conventional implant needles.U.S. Pat. Nos. 5,928,120 and 5,938,583 describe improvements to theconventional implant needles themselves. U.S. Pat. Nos. 4,763,642 and4,815,449 describe a bioabsorbable carrier for implanting a string oflow dose radioisotope seeds. U.S. Pat. Nos. 4,086,914, 5,242,373,5,860,909, 6,007,474, 6,102,844, and 6,213,932 describe manual seedinjector arrangements for a low dose radioisotope procedure that utilizedrop-in seed cartridges or seed magazines to supply the seeds directlyto an implant needle that is specifically adapted to such cartridges ormagazines.

U.S. Pat. No. 6,221,003 describes an elongated cartridge with a centralchannel that contains a plurality of seeds interspersed with a pluralityof spacers for loading a single implant needle; however, the seeds andspacers are manually loaded into the central channel using leaded glovesor tweezers. U.S. Pat. No. 6,280,472 describes an orbiturer for manuallypushing seeds from a central channel into tissue such that the implantsare selectably spaced from one another via a reciprocating carriagearrangement. The orbiturer also includes a mechanical detent arrangementthat serves as an indicator of the number of seeds that were implanted.PCT Publ. No. WO 01/66185 describes an alternative arrangement forloading a single implant needle in which a separate seed cartridge andspacer cartridge are manually advanced into corresponding slots in aloading tube such that a manually-operated plunger can dislodge the seedand spacer from chambers in the cartridges to load the implant needle.

Over the years there also have been numerous advancements in the designof equipment for use in high dose radioisotope procedures. U.S. Pat.Nos. 3,861,380, 4,851,694, 5,092,834, 5,120,973, 5,183,455, 5,272,349,and 5,800,333 describe various automated afterloaders that advance asource wire carrying a high dose radioisotope at the end into a cathetersystem for high dose radioisotope procedures. U.S. Pat. Nos. 4,150,298,5,147,282, 5,851,172 and 6,048,300 describe replaceable cartridgeassemblies that contain the source wire used in conjunction withspecifically adapted afterloaders.

Although the use of replaceable cartridges and automated afterloadershave been well received for use in connection with high doseradioisotope procedures, the standard techniques for low doseradioisotope procedures continue to utilize a series of implant needlesthat are manually loaded by a radiophysicist at the hospital just priorto the time they are manually inserted by the physician. There areseveral reasons for why this manual process has been the standard forlow dose radioisotope procedures.

The differences in the types of radioisotope sources do not favor theuse of existing manual drop in cartridges for low dose radioisotopeprocedures. The source wires used for high dose radioisotope proceduresuse only one or a small number of very high power radioisotope sourceshaving relatively long half-lives. As a result, it is cost effective andpractical to provide for a cartridge arrangement for such a small numberof high dose radioisotopes that can be preordered and maintained at thehospital well in advance of a procedure. In contrast, low doseradioisotope procedures have relatively short half-lives of theradioisotopes and it is preferable that the radioisotope seeds be sentto the hospitals just prior to their use. Because the number ofradioisotope seeds varies from procedure to procedure depending upon thedose plan, and because the cost of each low dose radioisotope seed issignificant, it is not cost effective to order many more radioisotopeseeds than will be used in a given procedure.

It is important to minimize the time of the procedure, both in terms ofthe exposure time of the physician to the low dose radioisotope seedsand in terms of the total time of the procedure from the economics ofmedical practice. In the case of brachytherapy treatment for prostatecancer, it is also advantageous to complete the procedure as quickly aspossible because the prostate gland can swell during the procedure,further complicating the implantation process. The existing drop-incartridge and seed magazine manual systems described above for low doseradioisotope procedures generally require a longer time to perform theimplant procedure than when conventional preloaded implant needles areused. This is because the radioisotope seeds are manually implantedone-by-one, rather than being delivered simultaneously as a group from apreloaded needle. The manual one-by-one techniques also can require morecare and precision to insure that all of the seeds for a given row areactually implanted in that row.

Due to the large number of low dose radioisotope seeds used in a givenprocedure (typically up to 150), the requirement that a radiophysicistat the hospital take a set of sample measurements of the strength of theradioisotope seeds to confirm that the seeds meet the requirementsspecified by the dose plan, and the need for the implanting physician tobe able to modify the dose plan at the time of implant, it is generallyconsidered that the flexibility afforded by manually loading the implantneedles just prior to the operation provides the best possible treatmentprocedure for the patient and the most economically efficient procedurefor the hospital.

More recently, systems that attempt to integrate the diagnostic processof establishing a dose plan using an ultrasound probe with a manualimplant needle grid have been proposed. The process of establishing adose plan for brachytherapy treatment is described, for example, in U.S.Pat. No. 6,095,975. In U.S. Pat. No. 5,871,448, a manual stepperarrangement for positioning the ultrasound probe is described. In U.S.Pat. No. 6,206,832, an apparatus for merging multiple ultrasound imageto assist in guiding implant needles is described.

In U.S. Pat. No. 6,129,670, an automated arrangement is described forutilizing the ultrasound probe to generate ultrasound image data that isused to generate a translucent volume image of the patient's body andthe prostate over which an image of the implant needles can besuperimposed. One embodiment of this patent briefly describes anautomated system for loading radioisotope seeds into implant needlesbased on a clinical plan that enables rapid treatment based onsubstantially real-time preplanning using rapid patient organevaluation. In this embodiment, a gravity fed bin arrangementselectively drops seeds into the rear end of a vertically orientedneedle. A pair of micro-controllers communicates with the computer thatgenerated the dose plan to be the dose plan and control the dropping ofthe seeds and spacers into the rear end of the needle by using anoptical sensor positioned along the passageway through which the seedsare dropped to monitor loading of each seed into the needle. Althoughthe needle loading is proposed to be automated in this manner, theimplantation of the loaded needles is accomplished manually using aconventional needle grid arrangement.

A modular device for implanting radioactive seeds through a needleimplanted in the body is described in EP 1 070 519 A1. An electroniccontrol device controls a pushing drive, a seed supply container, aspacer supply container and a multi-channel holder for seed-spacertrains. A tube connects the multi-channel holder and the needle throughwhich the seed-spacer trains are pushed by a wire in order to implantthem in the body, with the wire remaining in place while the needle iswithdrawn. In one embodiment, the seed-spacer trains are loaded andimplanted by a single unit. In another embodiment, the seed-spacertrains are preloaded into the multi-channel holder by a loading unit andthen the multi-channel holder is then transferred to an implantationunit. In this embodiment, a microprocessor is used to control the seedloading unit in response to a therapy planning program. Like U.S. Pat.No. 6,129,670, the loading of seeds and spacers to form the seed-spacertrains in EP 1 070 519 A1 is accomplished directly in response to thetherapy planning program executed that determines how the needles are tobe placed in the prostate and how many radioactive seeds are to placedin what order in each of the needles.

Other uses of automated arrangements for positioning ultrasound probesor for controlling biopsy needles have been proposed. U.S. Pat. Nos.4,649,925, 5,181,514, 5,282,472, 5,361,768, 5,540,649, and 5,552,645describe the use of automated arrangements for positioning of ultrasoundprobes. These automated arrangements typically include a stepper motorfor advancing and retracting the ultrasound probe within the rectum anda rotational control for rotating the probe once in position within therectum. U.S. Pat. Nos. 5,398,690, 5,415,169, and 5,830,219 describeautomated biopsy arrangements in which a biopsy needle is inserted underautomated control to obtain and extract a biopsy sample. These automatedsystems also include a single linear motion control and a rotationalcomponent control, and have an additional angulation control thatcontrols the orientation of the needle upon insertion.

More complicated and expensive three-dimensional automated controlsystems for surgical instruments also have been developed. U.S. Pat.Nos. 5,540,649 and 5,695,500 describe examples of automated surgicalsystems that feature multiple joints and arms to allow for control ofmotion in all three axis of a surgical instrument positioned at theworking end of these systems. The complexity and expense of thesethree-dimensional control systems have generally precluded their use inconnection with positioning systems for ultrasound probes and biopsyneedles.

Despite these improvements, the manual processes for low doseradioisotope procedures remains the standard for the reasons describedabove. It would be advantageous to provide for an automated implantationsystem for implanting low dose radioisotope seeds in a patient as partof a brachytherapy procedure that could overcome these problems andenhance the safety and efficiency of this process.

SUMMARY OF THE INVENTION

The present invention is an automated implantation system for implantinglow dose radioisotope seeds in a patient as part of a brachytherapyprocedure. A Z-axis automated motion control system and an X-Y axisautomated motion control system control a needle assembly. The X-Y axisautomated motion control system positions an insertion axis of theneedle assembly relative to the patient. The Z-axis automated motioncontrol system selectively moves the needle assembly along the insertionaxis to implant at least one radioisotope seed. This process is repeatedfor a plurality of locations on a base plane perpendicular to theinsertion axis.

A seed cartridge contains at least a plurality of radioisotope seedspreloaded into the cartridge, the needle assembly, and structure formounting the seed cartridge and the needle assembly in the carrierstructure. An implantation station has a base structure that initiallypositions the insertion axis relative to the patient. Preferably, thebase structure includes a base, a moveable assembly that includes theinsertion axis and is orientable independently of the base, and a standoperably connected between the base and the moveable assembly. Cartridgereceiving structure is defined along a portion of the insertion axis inthe moveable assembly to receive the cartridge.

The Z-axis automated motion control system selectively moves the needleassembly along the insertion axis and selectively advances at least oneradioisotope seed from the cartridge along the insertion axis when thecartridge is positioned in the cartridge receiving structure.Preferably, the X-Y axis automated motion control system selectivelymoves the moveable assembly in the plane perpendicular to the insertionaxis. A computer processor operably connected to at least the Z-axisautomated motion control system and the X-Y axis automated motioncontrol system has a user interface that displays information about theautomated implantation system and accepts commands from a user tocontrol the process of implanting the plurality of radioisotope seeds.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a preferred embodiment of the automatedimplantation system for implanting low dose radioisotope seeds andshowing the preferred embodiment of the replaceable cartridge of thepresent invention in place within the automated implantation system.

FIG. 2 is a perspective of an alternate embodiment of the automatedimplantation station with an enclosure over the moveable assembly.

FIGS. 3A and 3B are exploded perspective views of the preferredembodiment of the replaceable cartridge of FIG. 1.

FIG. 4 is a schematic representation of the various combinations ofradioisotope seeds and spacers as stored in the rotatable drum of thepreferred embodiment of the replaceable cartridge of FIG. 3.

FIG. 5 is a detailed perspective view of the moveable assembly of thepreferred embodiment of the present invention.

FIG. 6 is a detailed perspective of the replaceable cartridge with aneedle assembly in place.

FIGS. 7, 8, and 9 are front, top, and end plane views of the automatedimplantation station of FIG. 1, respectively.

FIGS. 10 and 11 are sectional views of the replaceable cartridge of FIG.6.

FIGS. 12 and 13 are graphic depictions of a preferred embodiment of auser interface screen of a display of the automated system of FIG. 1.

FIG. 14 is a perspective view of another embodiment of the automatedsystem of the present invention having a replaceable cartridge that doesnot include the stepper motors.

FIGS. 15, 16, and 17 are front, top, and end plane views of the moveableassembly of FIG. 4, respectively.

FIGS. 18, 19, and 20 are three different perspective views of apreferred embodiment of the implantation station of the presentinvention.

FIGS. 21, 22, and 23 are three different perspective views of apreferred embodiment of the moveable assembly of the present invention.

FIG. 24 is an exploded view of the cartridge of FIG. 6.

FIG. 25 is an exploded view of the capstan assembly of the cartridge ofFIG. 6.

FIG. 26 is a perspective view of a preferred embodiment of the moveableassembly.

FIGS. 27 and 28 are cross-sectional view of FIG. 26.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, an automated implantation system 10 for implantinglow dose radioisotope seeds into a patient is comprised of animplantation station 12 into which a replaceable cartridge 14 may bepositioned. A moveable assembly 16 is positioned in an appropriaterelation to the patient (not shown) for the brachytherapy procedure. Acartridge receiving structure 18 is defined in the moveable assembly 16along an insertion axis 20. A needle assembly 22 is moveable along theinsertion axis 20 (in a Z direction) and in a plane 21 definedperpendicular to the insertion axis (in both X and Y directions) by anautomated motion control system as will be described. Preferably, anultrasound probe 24 also carried by the moveable assembly 16 is moveablealong an axis parallel to the insertion axis 20.

Preferably, the implantation station 12 is a standalone unit thatincludes a base 15 and a stand 17 supporting the moveable assembly 16relative to the base 15 (as shown in FIG. 1) and a hinged cover 23 (asshown in FIG. 2) for the moveable assembly 16. All of these componentsare preferably formed of molded plastic or metal. Although theimplantation station 12 will be described as a standalone unit providingits own support and housing arrangements, it will be understood that theautomated implantation system 10 of the present invention is equallyapplicable to an arrangement in which the moveable assembly 16 would bemounted on a table or other platform or where the moveable assembly 16is hung from an arm or ceiling. Similarly, while the preferredembodiment of the automated implantation system 10 includes all of theelectronics, software, controls, and displays for operating theimplantation station as part of a single unit, the present inventioncontemplates that the various functions of these components could beperformed by separate devices in separate housings.

A computer processor 30 for the automated system is preferably amotherboard having a microprocessor, internal bus, a PCI-compatible bus,DRAM and EPROM or battery backed SRAM, with appropriate externalinterfaces or mated PC boards for a video interface, multiple channelIDE interfaces, a floppy disk interface, an ethernet interface, COM andLPT interfaces, an external bidirectional parallel port and a serialport. An automated motion control system 32 is preferably a Galil motioncontroller available from Galil Motion Control Inc. that interfaces tothe computer processor 30 via the PCI-compatible bus. The automatedmotion control system 32 with appropriate software drivers provides allfunctionality for the lowest level control of stepper motor position andfeedback sensors. A hard disc drive 34, floppy disk drive or highdensity removable media drive 36 and CD or CD-RW drive 38 are alsoprovided for storing data and information to be used by the automatedimplantation system 10.

A video display 40 that operates as the primary user interface ispreferably a 1280 by 1024 resolution flat 18.1 inch flat panel LCD witha resistive touch-screen, such as are available from National DisplaySystems. In this embodiment, an arm structure 41 positions the display40 in a position convenient for the user. Alternatively, a conventionalnon-touch-screen video display and mouse, keyboard or similar inputdevices could also be provided. Preferably, two separate joy stickcontrols 42, 44 are provided as direction control input mechanisms toallow a user to control at least the Z-axis direction of the automatedmotion control system 32. In this embodiment, the joy stick control 42is preferably a single Z-axis control input located near the videodisplay 40 that controls the advancement and retraction of the needleassembly 22 along the insertion axis 20. The joy stick control 44 is adual axis control input located on the stand 17 that can selectivelycontrol a variety of other automated motion functions for theimplantation station 12, including, for example, fine movement of theinsertion axis 20 to different locations in the X-Y plane 21, as well asgross movements of the moveable assembly 16 relative to the patient. Itwill be understood that a variety of alternative direction control inputmechanisms could also be utilized with the present invention, such asicon controls displayed on the video display 40, voice activatedcontrols processed by the computer processor 30, or switches, slides,dials, or similar mechanical controls.

Referring specifically to FIG. 5, the cartridge receiving structure 18of the preferred embodiment will be described. The cartridge receivingstructure 18 includes a U-shaped bracket 25 (FIG. 17) that rides on apair of rails 26 with each rail 26 of the bracket preferably beingdriven by one of a pair of synchronized stepper motors 27. The pair ofbrackets 25 and corresponding pair of stepper motors 27 are preferablyutilized to control any potential skew of the cartridge 14 as it ismoved along the insertion axis 20. Alternatively, a single stepper motorand single rail, a linear screw drive, a rodless cylinder, or any numberof other motion arrangements could be provided to drive the cartridge14.

Once in position, the implantation station 12 locks the cartridge 14 inplace using an electrical solenoid 29 to prevent inadvertent removal ofthe cartridge 14 during operation of the automated system 10. Locking isinitiated automatically once the presence of a cartridge 14 has beendetected in the cartridge receiving structure 18 and the user hasinitiated an implantation operation via display 40. Unlocking thecartridge is initiated by the user selecting a remove cartridgeoperation via display 40, but only after computer processor 30 hasconfirmed completion of any critical motions that are part of theimplantation operation and removed power to the cartridge 14.Preferably, the only other interface between the cartridge 14 and thecartridge receiving structure 18 is a multiple pin-type electricalconnector 28.

Preferably, a disposable guide bushing 31 is utilized at the distal endof the cartridge receiving structure 18 to house the distal end of theneedle assembly 22 while the proximal end of the needle assembly 22 canbe attached to the cartridge 14. In one embodiment, the needle assembly22 is prepackaged in the place within the guide bushing 31 and need onlybe screwed onto or otherwise connected to the cartridge 14. This allowsthe guide bushing 31 to be disposable. In this embodiment, the guidebushing 31 has appropriate mating structure within the cartridgereceiving structure 18. Preferably, a condom or other disposablemembrane would cover the exposed portion of the needle assembly 22 toreduce the possibility of contamination by body fluids. In an alternateembodiment, the needle assembly 22 could be threaded into a guidebushing that was part of the moveable assembly 16. In still anotherembodiment, a carrier structure could be created to hold both thecartridge and the needle assembly in a single arrangement that would beloaded together into the implant station.

As the stepper motors and associated encoder discs are contained withinthe cartridge 14, the need for extremely tight tolerance matches betweenthe cartridge receiving structure 18 and the cartridge 14 is minimized.In addition to the necessary control and sensor signals, the connector28 includes a ground and power connection to provide power to thecartridge 14. The presence of cartridge 14 in cartridge receivingstructure 18 is also detected via a contact on connector 28. Although anarrangement using a bracket 25 and pair of guide rails 26 that is drivenby a stepper motor 27 and is connected by the electrical connector 28and locked by an electrical solenoid 29 is the preferred embodiment forinterfacing the cartridge 14 with the cartridge receiving structure 18,it will be recognized that many other structures, such as channels,latches, pivoting arrangements, ball and detent locks, and orientations,such as horizontal or vertical, and connectors, such as optical,infrared, RF, slide contacts, array contacts or the like, could be usedto accomplish the same function of interfacing the cartridge 14 with thecartridge receiving structure 18.

Referring now to FIGS. 3A and 3B, one embodiment of the cartridge 14contains a plurality of radioisotope seeds and a plurality of spacerspreloaded into the cartridge. The cartridge 14 has at least one aperture50 into which at least a portion of the needle assembly 22 ispositioned. Preferably, the radioisotope seeds and spacers are loadedinto holes or chambers 52 located around the periphery of a rotatabledrum 54. In this embodiment, the cartridge 14 includes a pair of steppermotors within the cartridge. A first stepper motor 56 rotates therotatable drum 54. It will be seen that stepper motor 56 preferablydrives rotatable drum 54 directly without any intervening gearingarrangement.

A second stepper motor 58 has a capstan assembly 60 that rotates inengagement with a trochar needle 62 to slide the trochar needle 62. Forthe rotatable drum 54, an encoder detector 64 detects the position of acorresponding encoder disc 66 that is then communicated back toautomated motion control system 32 (FIG. 1). Preferably, the steppermotor and encoder are selected such that the stepper motor steps in fullsteps with relation to the distance between chambers around theperiphery. The alignment of the aperture 50 to the chambers 52 in thedrum 54 is preferably initially accomplished at the time of assembly. Itwill also be seen that other motor drives other than stepper motorscould be used with equivalent success in the present invention, such asservo motors, worm driven motors, or DC motors with appropriate indexingcontrol.

In an alternative embodiment, an encoder with a higher degree ofresolution can be used and the stepper motor can be incremented in lessthan full steps. In this embodiment, a first encoder for the rotatabledrum 54 generates a positional feedback signal of an index of thechambers of the rotatable drum 54 relative to the line of travel of thecapstan assembly 60, and a second encoder with a second encoder disc forthe capstan assembly 60 that generates a positional feedback signal of aposition of the elongated member along the line of travel.

Referring to FIG. 6, the needle assembly 22 is preferably comprised ofthe trochar needle 62 coaxially located within a canula 63. At least thetrochar needle 62 is preferably replaceably mounted in the cartridge 14to permit removal and replacement of the trochar needle 62 when theprocedure is completed. Preferably, the canula 63 is also replaceablymounted to the cartridge 14 to permit removal and replacement of thecanula 63 when the procedure is completed. Although a trochar needle 62within a canula 63 is the preferred embodiment of needle assembly 22, itwill be recognized that other embodiments of the needle assembly 22could be provided, such as a coaxial arrangement of a push rod inside anouter needle where the outer needle does the cutting.

Referring again to FIG. 3, a series of position sensors 72 arepositioned in line with the trochar needle 62 to detect the travel oftrochar needle 62 as it is driven by capstan system 60 through its lineof travel. The sensors 72 are connected to sensor circuitry 74 tocommunicate this position information to the automated motion controlsystem 32. Each of the encoder detector 64 and sensor circuitry 74 areelectrically connected to a circuit board 76 which has an appropriateconnector 78 for mating with and connecting with a correspondingconnector 28 (FIG. 5) in the cartridge receiving structure 18 of thehousing 12.

Preferably, the circuit board 76 is provided with an electricallyerasable programmable read-only memory (EEPROM) 79 or similarnon-volatile memory to store parameters and other data that are uniqueto the particular cartridge 14 and to the particular patient and doseplan that has been developed for that patient. The contents of EEPROM 79are set up initially during loading and calibration of the cartridge 14at the factory. These contents are updated by the automated system 10 soas to continually reflect the current state of the cartridge 14. Forexample, when the radioisotope seeds and/or spacers are ejected from agiven chamber 52, then the data on the EEPROM 79 is updated to reflectthat the given chamber 52 no longer contains any radioisotope seedsand/or spacers. Preferably, the EEPROM 79 is capable of storing patientand hospital identification information, as well as seed inventory andmanufacture information. Optionally, the EEPROM 79 could also store thepredetermined dose plan for the particular patient.

In the preferred embodiment, various housing elements enclose thecartridge 14 to create a single, enclosed drop-in cartridge to simplifyoperation and handling of the cartridge as shown in FIG. 3. Preferably,the various housing elements are formed of machined stainless steel toenhance the protective aspect of the housing. Alternatively, the housingcould be formed of materials other than stainless steel. For example,the housing elements could be molded plastic with appropriate pieceshaving an internal lead lining or the like to provide sufficientshielding. Although the preferred embodiment is described as a single,enclosed drop-in cartridge, it will be understood by those skilled inthe art that some or all of the functional components of cartridge 14may be separately enclosed or left unenclosed and operably connectedtogether to accomplish the same functionality, such as allowing formating with the cartridge receiving structure 18 and protecting movementof the trochar needle 62 along its line of travel.

In the embodiment of the cartridge 14 as shown in FIG. 3, a sleeve 80encloses the rearward travel of trochar needle 62. Cover 81 is aone-piece unit that covers the capstan assembly 60 and its associatedcomponents. A capstan motor mount 82 provides a mounting base for mostof the main components of cartridge 14, including circuit board 76 andencoder detector 64. Housing 83 houses the stepper motor 56 and therotatable drum 54. A cover plate 84 mounts to the housing 83. The motormount 82 and the cover 81 are secured by internal screws (not shown)that are accessed when the cover plate 84 is removed. A front plate 85covers the circuit board 76 and is also mounted with screws betweencover plate 84 and cover 81. A needle housing 86 is also screwed on tothe cover plate 84 and includes the aperture 50 through which the needleassembly 22 accesses the cartridge 14.

FIGS. 6, 10, 11, 24, and 25 show various views of a preferred embodimentof the cartridge 14 that is similar to the cartridge 14 as described inconnection with respect to FIG. 3. The primary differences in thisembodiment relate to the nature of the capstan assembly 60 for drivingthe trochar needle 62 and the construction of the portion of thecartridge 14 that attaches to the needle assembly 22. Due to the desireto location the insertion axis 20 as closely as possible to the axis ofthe ultrasound probe 24, the cartridge 14 of the preferred embodiment ofthe present invention minimizes the depth of the bottom structure of thecartridge 14. This allows the cartridge 14 to sit low within thecartridge receiving structure 18 and immediately above the ultrasoundprobe 24. Consequently, the aperture 50 is preferably located on thevery bottom of the drum 54. The structure of the cartridge 14 at thefront of the cartridge that attaches to the needle assembly 22 ispreferably made as wide as the structure at the rear of the cartridgewhich houses the stepper motor. The only depth created on the bottom ofthe cartridge 14 is the depth necessary for the circuit board connectingthe sensor 72 and an associated cover.

In addition to the advantages afforded by constructing cartridge 14 as asingle, enclosed drop-in cartridge, the preferred embodiment ofcartridge 14 is designed with minimum piece parts to allow for easydisassembly and sterilization to allow for potential re-use. Once thevarious covers and circuit assemblies are removed, the remainingportions of cartridge 14 are cleaned with alcohol or hydrogen peroxideto remove bioburden. When reassembled, the entire cartridge 14 ispreferably sterilized with a gas sterilization technique. The ease ofdisassembly also provides a convenient mechanism by which emergencyremoval of the radioisotope seeds can be accomplished, simply byremoving cover plate 84 and dumping the radioisotope seeds and spacersinto an appropriate container.

The use of a rotatable drum 54 also affords important advantages to thepreferred embodiment of the present invention. The positioning of thechambers 52 around the periphery of drum 54 reduces the concentration ofradiation sources at any given point and provides an optimum separationof radioisotope seeds from each other, thereby enhancing the safety ofcartridge 14.

In the preferred embodiment, each chamber 52 is long enough toaccommodate any of a combinatorial set of radioisotope seeds, spacersand plugs. As shown in FIG. 4, various combinations of radioisotopeseeds 110, full-length spacers 112, and partial-length spacers 114 whichcan serve as blanks can be positioned within a given chamber 52. In thisembodiment, the length of one radioisotope seed 110 or one blank 114 is4.5 mm and the length of one full-length spacer 112 is 5.5 mm. As willbe apparent, the selection of the lengths of each of the seeds 110, andspacers 112, 114 allows for various combinations to be utilized thathave the same overall length when positioned in an implant needle of 10mm for seed and spacer. The particular combination of each for a givencartridge is optimally determined at the time that the cartridge 14 ispreloaded in accordance with a predetermined dose plan. This informationcan then be utilized by the automated station 10 to load the implantneedles in accordance with that predetermined dose plan.

In the preferred embodiment, the rotatable drum 54 is provided with 200chambers 52 spaced equidistant about the periphery of the rotatable drum54. The optical encoder disc 66 preferably has 400 or 1600 lines ofresolutions that yield a resolution of 2 or 8 counts per chamber 52. Inan alternate embodiment with higher resolution as previously described,72,000 lines of resolution are used which yields a resolution of 360counts per chamber 52. A home reference is provided by an index channelon the encoder disc 66. The alignment of the aperture 50 to the chambers52 in the drum 54 using the index channel is preferably accomplished atthe time of assembly. In the high-resolution embodiment, an offset to afirst chamber location clockwise from the home reference is stored as aparameter for the cartridge 14 to allow for individual cartridgetolerance calibration. Alternatively, an optical sensor could be used tolocate the center of a chamber 52 for purposes of calibrating an index.

In operation, the automated motion control system 32 uses the firststepper motor 56 and encoder detector 64 to establish a reference to thefirst seed drum chamber 52. Motion of the drum 54 may take placebidirectionally (i.e., clockwise or counterclockwise) and as rapidly aspossible in order to move to the nearest desired chamber location asdetermined by the computer processor 30 and automated motion controlsystem 32 in the shortest possible time. When requested by the computerprocessor 30, the automated motion control system 32 will index to thecenter of the desired chamber location in preparation for transfer ofthe contents of that chamber 52 to the implant needle. The drum 54 willremain at this location until it is commanded to a new position.

When a request for a seed transfer is generated by the computerprocessor 30, the automated motion control system 32 activates thecapstan assembly 60 to retract the trochar needle 62, thereby allowingthe drum 54 to be rotated freely. When the drum 54 has been indexed tothe desired chamber location, the automated motion control system 32instructs the second stepper motor 58 to move the trochar needle 62forward to push the contents of the chamber 52 out of the drum 54 andinto the needle assembly 22.

The trailing one of the position sensors 72 is provided along the pathof material transfer to allow for detection of the leading edge of thecontents with relation to the tip of trochar needle 62. As the contentsof a given chamber 52 are moved by the position sensor 72, the totallength of the contents may be determined. This configuration allows fora verification of the length of the contents of a given chamber 52 withthe information the automated system has about what should be in thatchamber 52 to prevent potential implants of the wrong seeds. In theevent of an early or late activation of the sensor 72 by the tip of thetrochar needle 62 in relation to the expected activation based on theanticipated length of the contents of that given chamber 52, an alarm orerror message would be passed to the computer processor 30.

Although the drum 54 has been described as the preferred embodiment ofthe positional member of the cartridge 14 with its movement controlledby first stepper motor 56, it should be understood that other forms ofthis positional member and other motor arrangements would also workwithin the scope of the present invention. For example, the positionablemember could be an X-Y grid of chambers with a pair of stepper motorsused to drive the grid in X-Y directions to position the desired chamberin line with the aperture 50 and trochar needle 62. Although steppermotors, such as stepper motor 56, and encoders, such as encoder disc 66are a convenient and economical manner of implementing the presentinvention so that it may be controlled by an external microprocessorarrangement, it will be recognized that other arrangements such asgears, drive belts and clutched motor shafts could be used in place ofthe stepper motor, and that contact sensors, optical sensors or registryfrom a known starting point could also be used in place of the encoder.It will also be seen that while the preferred embodiment interfaces withan external microprocessor, it would also be possible to incorporate amicroprocessor into the cartridge itself and to communicate externallyby telecommunications, radio communications or the like, instead of byelectrical connectors.

Referring now to FIGS. 6 and 25, a preferred embodiment of the capstanassembly 60 will be described. A pair of capstan drives 120 arepreferably positioned above and below the line of travel of trocharneedle 62. In this embodiment, a stepper motor 58 drives a drive shaft121 that is coupled via gears to an upper member 122 of the capstandrives 120. A lower member 123 of the capstan drives 120 is preferablyheld in a biased pivot arm 124 biased by a spring 125. The pivot arm 124pivots to allow the trochar needle 62 to enter the capstan assembly 60.Once engaged, the channel guides the trochar needle 62 as it isfrictionally held between the upper member 122 and lower member 123 ofeach capstan drive 120. Each member 122, 123 preferably includes aradial groove 126 in which the trochar needle 62 rides as it is moved.In this embodiment, another capstan 127 is connected to an encoder disc128 by a pinion 129 for driving the canula 63. This arrangement allowsfor capstan drives 120 to drive the trochar needle 62 forward andbackward with potential slippage in the event that the trochar shouldencounter excessive resistance. The capstan 127, however, is not beingdriven and therefore accurately records the movement of trochar needle62 past this position.

In this embodiment, the capstan drives 120 and 127 are held within acapstan body 130. The capstan body 130 is spring biased by springs 131at the end of mounting rods 132. A cover plate 133 holds the capstandrives 120 and 127 within the capstan body 130. A force sensor 134 isoperably connected to at least the trochar needle 62 and to the needleautomated motion control system. The force sensor 134 senses whether theneedle assembly 22 encounters resistance that exceeds an expected forceassociated with piercing tissue when the needle automated motion controlsystem advances the trochar needle 62. When the force sensed by theforce sensor 134 exceeds the expected value, the force sensor 134 causesthe needle automated motion control system to stop advancing the needleassembly 22 along the insertion axis 20. In a preferred embodiment, theforce sensor 134 is a load cell mounted at the front of the capstanassembly 60. The spring biased mounting rods 132 are prebiased to holdthe capstan assembly 60 against the load cell 134 at a predeterminedpressure. The compliant mount of the capstan assembly 60 provides for aminimum travel distance in the event that the trochar needle 62encounters resistance that exceeds the force expected for piercingtissue. The compliant mount thereby forms a safety buffer that allowsthe trochar needle 62 to retract. The force sensor 134 also senseswhether the needle assembly 22 has advanced into a non-tissue region.When such an action is sensed, the force sensor 134 no longer registersthe prebiased pressure and effectively notifies the user that the needleassembly 22 has advanced into the non-tissue region. Preferably, atravel of up to 3 mm is allowed by the compliant mount of the capstanassembly 60.

A positive travel limit is preferably established using a first opticalsensor 136 that is part of the structure of capstan assembly 60 whichdetects the back of the trochar needle 62 passing through a definedpoint. A negative travel limit for the line of travel of trochar needle62 is established by a second optical sensor 137 that doubles as a homereference. Preferably, the travel limits do not disable the secondstepper motor 58, but rather send an indication to the automated motioncontrol system 32 that the respective travel limit has been exceeded.Once zeroed in relation to the home reference, the trochar needle 62 ismoved forward and into an open chamber 52 in the drum 54. This serves asa loose mechanical lock to prevent the drum 54 from being rotatedunintentionally.

The canula 63 preferably includes an annular wiping seal 138 positionedalong the insertion axis 20 at a distal end of a staging area 140. Thecanula 63 also preferably includes a second annular wiping seal 139positioned along the insertion axis 20 at a proximal end of the stagingarea 140. In one embodiment as shown in FIG. 2, the needle assembly 22preferably includes a bellows structure arranged around the canula 63 tocollect body fluids and materials when the needle assembly 22 iswithdrawn from the patient.

In the preferred embodiment, the implantation station 12 does notinclude a radiation sensor for safety reasons owing to the high voltagesource required for such radiation sensors and the close proximity thatsuch a high voltage source would need to be in relation to the needleassembly 22 that will be inserted into the patient. Accordingly, thepreferred embodiment utilizes a modified version of the loading stationas described in the parent application to perform an on-siteverification of the contents of the cartridge 14. The cartridge 14 isplaced in a second cartridge receiving structure in the loading stationwithout the needle assembly 22 attached and a transition tube is used toconnect the cartridge 14 with an empty cartridge located in a firstcartridge receiving structure in the loading station. The loadingstation then empties a selected portion of the radioisotope seeds fromthe cartridge 14 into the empty cartridge and then reloads this selectedportion back into the cartridge 14. During this process, the radiationsensor in the loading station can assay the strength of the selectedportion of the radioisotope seeds to verify that the radioisotope seedsin the cartridge 14 are the correct seeds to be implanted in thepatient. This process could also be utilized to load the cartridge 14 orto alter the contents of the cartridge 14 at the hospital site. In analternative embodiment, a separate radiation sensor could beincorporated into the implantation station and the cartridge 14 providedwith a second aperture through which a separate push rod or trochar, notin electrical contact with the trochar needle 62, could advance theradioisotope seeds past the radiation sensor.

Referring to FIGS. 21-23, the moveable assembly 16 includes a Z-axismotion system 150 that selectively moves the cartridge receivingstructure 18 and the needle assembly 22 along the insertion axis 20.Preferably, the Z-axis motion system 150 is controlled by the automatedmotion control system 32, which in turn is directed by the computerprocessor 30, all of which together can be thought of as a Z-axis motioncontrol system. The Z-axis motion system 150 selectively ejectsradioisotope seeds from the aperture 50 of the seed cartridge 14 intothe needle assembly 22 when the seed cartridge 14 is positioned in thecartridge receiving structure 18. The Z-axis motion system 150preferably moves the cartridge receiving structure 18 and the needleassembly 22 together to maintain a relative position between the seedcartridge 14 and the needle assembly 22 along the insertion axis 20.Preferably, the seed cartridge 14 and needle assembly 22 have a totaltravel movement of between 7-8 inches.

As shown in FIG. 25, the Z-axis automated motion control system 150preferably includes a needle automated motion system 152 that controlsthe capstan assembly 60 to drive the trochar needle 62 and a canulamotion system 154 that controls the canula 63. In the preferredembodiment, the canula motion system 154, the canula 63 is fixedrelative to the cartridge 14 and the canula motion system 154 moves theentire cartridge 14. The needle motion system 152 and the canula motionsystem 154 cooperate to initially move the trochar needle 62 and thecanula 63 along the insertion axis 20 by repetitively advancing thetrochar needle 62 a distance beyond the canula 63 and then advancing thecanula 63 an approximately equivalent distance. The distance the needlemotion system 152 advances the trochar needle 62 beyond the canula 63 ispreferably between about 0.5 and 2.0 centimeters.

In particular, the needle motion system 152 and the canula motion system154 cooperate to initially move the trochar needle 62 and the canula 63along the insertion axis 20 until the needle assembly 22 is inserted adesired depth into the patient. The Z-axis automated motion controlsystem 150 selectively ejects a radioisotope seed 110 and a spacer 114into the canula 63 as a pair oriented longitudinally along the insertionaxis 20 and advances the pair along the insertion axis 20 by pushing thespacer 114 with the trochar needle 62. To load the pair, the needlemotion system 152 preferably withdraws the trochar needle 62 once thecanula 63 is positioned as desired to accept a plurality of pairs eachconsisting of a radioisotope seed and a spacer in the canula 63. Eachpair is moved along the insertion axis 20 to a staging area in thecanula 63 proximal to the distal end of the canula 63 until all of thepairs for a current location of the canula 63 are in the staging areaafter which the needle motion system 152 advances all of the pairs alongthe insertion axis 20 to the distal end of the canula 63. The canulamotion system 154 withdraws the canula 63 once all the radioisotopeseeds are positioned. The needle motion system 152 keeps the trocharneedle 62 in place until the canula 63 is withdrawn. In a preferredembodiment, there are three optical sensors 72 (FIG. 10) that sense theposition of the trochar needle 62 as fully withdrawn, indexed into thedrum 54 or just extended (approximately 3 mm) past the drum 54 into thestaging area 140.

The moveable assembly 16 also preferably includes an X-Y axis motionsystem 160 that selectively moves at least the cartridge receivingstructure 18 and the needle assembly 22 in the base plane 21 that issubstantially perpendicular to the insertion axis 20. The X-Y axismotion control system 160 preferably moves the cartridge receivingstructure 18 and the needle assembly 22 together to maintain a relativeposition between the cartridge receiving structure 18 and the needleassembly 22 in the base plane 21. The X-Y axis motion control system 160includes an X-axis stepper motor 161 mounted on a top rail 162 on aU-shaped hanger 163 from which the cartridge receiving structure 18depends. The X-axis stepper motor 161 moves the hanger 163 left andright relative to the patient. The base arms of the hanger 163 includechannel structures 164 that are connected to the drive mechanism of aY-axis stepper motor 165 that can move the hanger structure 163 up anddown relative to the patient. Preferably, a single motor, two drivescrew arrangement is used with a pair of corresponding drive rails toprevent any offset in movement from one side to the other of the hangerstructure 163. In a preferred embodiment, the drive rails are splitdrive rails that move apart as the hanger structure 163 is lowered tominimize the length of the corresponding base plate. Preferably, a pairor rotatable bearings 166 mount the hanger structure 163 in such a waythat a tilt stepper motor 167 can tilt the orientation of the hangerstructure 163. This allows the angle of the moveable assembly to beadjusted. In a preferred embodiment, the tilt stepper motor can providea range of tilt of 10 degrees above horizontal to about 45 degrees belowhorizontal.

The moveable assembly 16 also preferably includes a manual rotationalmotion arrangement 180 connected to the moveable assembly 16. Therotational arrangement 180 pivots the moveable assembly 16 about avertical axis relative to the base 15. Preferably, a rotation of between5-10 degrees on each side of the center axis is allowed to enable themoveable assembly 16 to be properly positioned with respect to thepatient. A knob 181 tightens or loosens the rotational arrangement 180to turn the moveable assembly 16. A manual lateral adjustment is alsoprovided to allow for manual adjustment from side to side of themoveable assembly 16 relative to the patient. Again, a knob 182 tightensor loosens the manual lateral adjustment to allow the moveable assemblyto slide laterally.

In a preferred embodiment, the computer processor 30 adjusts the baseplane 21 in response to a user directive and all subsequent radioisotopeseeds placed by the implantation system 10 are placed at a depthdetermined from the adjusted base plane 21. Alternatively, computerprocessor 30 can monitor a position of an organ being treated in thebrachytherapy procedure and selectively adjusts a base plane 21 positionof the Z-axis automated motion control system 150 in response tomovement in the position of the organ during the brachytherapyprocedure.

The position of the organ is preferably monitored with an ultrasoundprobe 24. The position of the ultrasound probe 24 is controlled by asecond Z-axis automated motion control system 170 such as a steppermotor of linear screw drive coupled to a motion controller such asmotion controller 32. The second Z-axis automated motion control system170 selectively moves the ultrasound probe 24 along a probe axis 19 thatis generally parallel to the insertion axis 20. The computer processor30 preferably executes a dosimeter software routine that develops a doseplan for the patient based on images provided by the ultrasound probe24. The ultrasound probe 24 is preferably removably mounted within acarrier structure 172 defined on the moveable assembly 16. Preferably,the carrier structure 172 includes a mechanism that allows for rotationof the ultrasound probe 24 relative to the probe axis 19 and selectivelylocks the ultrasound probe 24 in a desired rotation in response to acommand from the computer processor 30. Preferably, the ultrasound probe24 has a total travel distance similar to the seed cartridge 14 of about7-8 inches.

The ultrasound probe 24 further includes an outer rigid sheath 186coaxial with the ultrasound probe 24. The Z-axis automated motioncontrol system 170 initially positions the outer sheath 186 and theultrasound probe 24 in the patient. The Z-axis automated motion controlsystem 170 also moves the ultrasound probe 24 along the probe axis 19and within the sheath 186 to generate ultrasound images along the probeaxis 19. The purposes of the sheath 186 is to stabilize the prostategland which tends to ride on top of the ultrasound probe 24 as theultrasound probe 24 is inserted in the patient's rectum. If theultrasound is withdrawn or moved during the procedure, there is atendency for the prostate gland to tip or slid off the end of theultrasound probe, thereby affecting the subsequent placement andlocation of radioisotope seeds. By utilizing a relatively rigid, yetthin ultrasound sheath 186, the preferred embodiment of the presentinvention solves this problem in that the prostate gland remains in aconstant position relative to the ultrasound sheath 186, regardless ofwhere the ultrasound probe 24 is moved within the sheath 186.

The computer processor 30 preferably captures and stores at least oneimage from the ultrasound probe 24 each time the needle assembly 22 islocated at a different position in the plane 21 perpendicular to theinsertion axis 20. The computer processor 30 also preferably capturesand stores at least one image from the ultrasound probe 24 when theneedle assembly 22 is moved forward along the insertion axis 20 to adistal most location where radioisotope seeds will be placed.

The computer processor 30 includes an autocalibration routine thatcalibrates an XYZ relationship of the ultrasound probe 24 to the needleassembly 22 each time a different ultrasound probe is used with theautomated implantation system 10. Preferably, the tilt mechanism allowsthe moveable assembly 16 to be tilted downward at an angle ofapproximately 45 degrees so as to allow the ultrasound probe 24 to beadvanced into a container of water for example to test and calibrate thenew ultrasound probe.

The stand 17 includes a gross vertical adjustment mechanism 188. Thegross vertical adjustment mechanism 188 adjusts a vertical height of themoveable assembly 16 relative to the base. Preferably, an up and downtravel of up to 12 inches is provided The gross vertical adjustmentmechanism 188 is preferably motorized. The base 15 also preferablyincludes a set of retractable wheels 190 (FIGS. 7 and 9) that allow theimplantation station 12 to be moved when the wheels 190 are extended andprovide a stable position for the implantation station 12 when thewheels 190 are retracted. The automated implantation system 10preferably includes alternative power sources. A primary power sourceconnection 192 plugs into an external outlet and a secondary powersource is supplied from a battery 194 housed in the stand 17. Thesecondary power source is configured to replace the primary power sourcein the event that the primary power source 192 is unplugged from theexternal outlet.

In one embodiment, a set of LEDs 196 are provided on the moveableassembly that are targeted to project a beam of light a predetermineddistance in front of the guide bushing 31 at a common triangulatedpoint, for example. The intersection of these beams of light define atarget point that is a defined distance in front of the guide bushing 31along the insertion axis 20 for positioning the location of theinsertion axis 20 relative to the patient.

Referring now to FIGS. 12 and 13, a preferred embodiment of the userinterface 200 as presented on display 40 (FIG. 1) will now be described.Preferably, the display 40 is a touch screen display and the computerprocessor 30 utilizes a Windows® NT operating system with a Radisys® InTime environment. To a user, however, the user interface 200 preferablyappears as a dedicated virtual machine having a single primarytouch-screen user screen as shown in FIG. 12. Although the preferredembodiment of the present invention will be described in connection witha touch-screen user interface 200, it will be recognized that variousother user interfaces, such as conventional video displays, LCD displaysor specialized displays may also be used with the present invention. Inaddition, it would be possible to provide for an audio-controlled userinterface coupled with an optional display screen to allow forvoice-activated control of the loading process.

In the preferred embodiment of user interface 200, a series of dedicatedtouch-activated buttons 201 to 206 are positioned to always remainvisible on the left side of the display. The user interface 200 ispreferably designed to provide a very flat icon-based menu structurewith minimal overlay windows where all of the functions controlled by auser are accessible though each touch screen inputs. A virtual keyboardmay be selected to enter alphanumeric data. Alternatively, a mouse andkeyboard may be connected to the computer processor 30 to enter suchdata. Another equivalent input device is a joystick or game port pad orequivalent pointing/directional input device. Preferably, each of thebuttons 201-206 has an icon on the top half of the button and acorresponding text message on the bottom half of the button.

A status icon 210 is preferably displayed along the left of userinterface 200 to display status messages such as Cartridge Detected,Reading Inventory, Running Diagnostics, Verifying Sensors, CartridgeReady, Printing and the like. Once a cartridge 14 has been successfullyloaded and locked into the cartridge receiving structure 18, at leastthe patient name information from the EEPROM 79 of that cartridge 14 isdisplayed in the top left corner of the user interface 200. Additionalpatient information can be accessed through button 212. In a preferredembodiment, the system status area 210 is also used as a multi-mediahelp screen that can display information about using the system 10, aswell as general information about the particular brachytherapy procedureto be performed. A volume control 216 is provided to convenientlycontrol the audio volume of multi-media information displayed on thestatus area 210.

The primary display in the main part of the user display 200 is theloading pattern grid 220 that replicates an interactive grid of how theradioisotope seeds are to be implanted in a format that is similar tothe paper format currently used for prostate cancer brachytherapyprocedures. In this format, the numbers along the left side of grid 220represent the height in centimeters and the letters represent the widthin 0.5 centimeter increments (1.0 centimeters between capital letters)of the locations where the radioisotope seeds are to be inserted from areference base axis that would be located at 0.0. The open circle icons222 at the intersection of each of these coordinates represents achamber in an implant grid that is used to implant the series of implantneedles 230. Each of the icons 224, 226, 228 in the center of grid 220represents a row of radioisotope seeds to be implanted with the numberin the center of the icons 224, 226, 228 indicating the number ofradioisotope seeds 110 that are planned for that location. The circleicons 224 are for needles in which the seeds 110 are spaced at regularintervals using full-length spacers 112. The triangle icons 226 are forneedles in which the seeds 110 are spaced at regular intervals, but areoffset or staggered by using at least one partial-length spacer 114. Thesquare icons 228 represent those locations in which the seeds 110 arenot spaced at regular intervals due to the staggering of partial lengthspacers 114 and full-length spacers 112.

The grid 220 is active, as shown in FIG. 13, when the Edit/Add Needlesbutton 232 is activated. The currently active location is indicated bythe message 233 at the upper right corner of the grid 220 and by theintersecting lines 234 that highlight that coordinate in the grid. Auser selects a different currently active needle location by pointing tothat location. In one embodiment, the status of each of the icons 224,226 and 228 are conveniently shown in the colors as indicated in thescoreboard area 240. The scoreboard area 240 is dynamically updated bythe computer 30 to reflect the planned, loaded, not yet loaded,cartridge inventory, extras and discards that the user has available orhas used. The Edit control area 244 allows a user to select retractionplane depths and number of seeds for the active needle location. Oncethe desired configuration is selected, the user accepts theconfiguration for the active needle location by entering button 246.Alternatively, the information for this location can be discarded byselecting the cancel button 248.

Once a user activates the Implant Needle button 230, as shown in FIG.12, the X-Y automated motion control system 160 position the insertionaxis 20 at the location indicated for the selected icon. Once themoveable assembly 16 is in position at the proper insertion axis 20, theneedle automated motion control system 152 and the canula automatedmotion control system 154 repetitively advance the needle assembly 62 adistance beyond the canula 63 along the insertion axis 20 and thenadvance the canula 63 that same distance until the canula 63 ispositioned at a desired depth relative to the base plane. The needleautomated motion control system then withdraws the trochar needle 62once the canula 63 is positioned at the desired depth to accept aradioisotope seed. Finally, the needle automated motion control systemadvances the trochar needle 62 to position the radioisotope seed in thecanula 63 at the desired position.

As a location is implanted, position indicators 252 and 254 in theneedle icon 250 represent locations in the implant needle in whichradioisotopes 110 and spacers 112, 114 may be loaded. As the implantingprocess progresses, seed icons 252 and spacer icons 254 are displayed inthe respective position indicators where those items are positioned inthe needle assembly 22.

The Input Dose Plan button 201 allows a user to input a predetermineddose plan. Two input options are provided, a Manual Input option and aLoad File option. In the Manual Input option, the grid 220 is displayedwith no predetermined dose plan overlayed. In this mode, the user wouldselect a desired location and then use the Edit/Load Needle button 202to indicate how the needle assembly should be filed corresponding tothat location. This process would then be repeated for each location tobe implanted via this manual option. In the Load File option, a pop-upwindow is displayed showing the default dose plan that was used togenerate the configuration of contents of the particular cartridge 14.In a preferred embodiment, a compact disc (CD) is delivered along withthe cartridge 14 to the hospital where the procedure is to be performedand the default dose plan is contained on this CD and is read by the CDplayer 38.

In another embodiment, a compressed version of the default dose plan isstored on the EEPROM 79 in the cartridge 14. If the automated system 10was used during the generation of the dose plan at an initial planningvisit or at the time of the procedure, then the dose plan would bestored on the hard drive 34. Alternatively, the default dose plan couldbe stored on a floppy disc and read by the floppy disc drive 36 or couldeven be stored on a remote location and accessed by an externalinterface, such as by an encoded transmission over the Internet or overa private dial-up network. If the user desires to override the defaultdose plan and select another dose plan, the pop-up window would allowthe user to search the various drives accessible by the automatedstation to locate an appropriate dose plan file. Preferably, the defaultdose plan is stored in a proprietary text file format adapted for use bythe software running on the computer processor 30.

Alternatively, the computer processor 30 could translate the outputfiles of any of a number of dose planning software packages to theproprietary text file format as part of the process of loading the doseplan. Once an appropriate file has been selected, the user can load theselected file as the dose plan and the details of that dose plan arethen displayed on the user interface 200. Alternatively, the computerprocessor 30 could be provided with the dosimetry software package and auser could develop the dose plan directly on the computer processor 30either prior to the procedure or during the procedure. For example, thedose plan could be modified as the procedure progresses in response toneedles that have been loaded. In this embodiment, a common filestructure could be shared between the dosimetry software and the controlsoftware running on the computer processor 30 for controlling implantingof the radioisotope seeds.

The Unlock Cartridge button 203 is used to instruct the automated systemto initiate the process of preparing for the cartridge 14 to be removedfrom the cartridge receiving structure 18. Various checks are performedby the computer processor 30 to insure that certain tasks are completed.These tasks include confirmation that no implant needles are in thecartridge, a verification that the current inventory of the seeds 110 inthe drum 54 is stored in EEPROM 79, a homing function for the trocharneedle 62 into an empty chamber 52 in drum 54 to lock the drum 54 intoposition. After these tasks are completed, power would be shut off tothe cartridge 14 and the solenoid 29 is deactivated to unlock thecartridge 14. A pop-up message is displayed to the user instructing themto manually remove the cartridge 14 from the cartridge receivingstructure 18 and providing for an option to cancel this operation.Preferably, a countdown timer is shown during which time the user wouldbe able to manually remove the cartridge 14 and after which the solenoid29 would be engaged again to relock the cartridge 14 in place. Thecontact on the electrical connector 28 is monitored to confirm that thecartridge 14 has been removed and the pop-up windows are closed once thecartridge 14 has been removed.

The System Setting button 204 allows the user to view and edit variousparameters of the automated system 10, including motion controlparameters and display preferences.

The Reports button 205 allows the user to print out certainpredetermined reports for the automated system 10, including a dose planreport, a calibration report, a case summary and a system diagnosticreport. These reports may be printed directly over the externalconnections for computer processor 30, may be stored to a file for laterprinting or review. The user may be provided with certain formattingpreferences and printing options to customize certain details of thepresentation of these reports.

The Exit button 206 allows the user to exit or switch from theimplantation application software back to the operating system softwarerunning on the computer processor 30. This button 206 can either beconditioned on a proper shutting down of the automated system 10,including removal of the cartridge 14, or it can allow for an option toswitch to another application that could be running on computerprocessor 30. In one embodiment of the present invention, the computerprocessor 30 is provided with dose planning software that would be usedby the physician to create the predetermined dose plan that is to beused by the needle loading application software.

In another embodiment, the computer processor 30 is provided with doseplanning software and with image management software that can captureultrasound images from the rectal ultrasound probe 24. In thisembodiment, the motherboard of the computer processor 30 is providedwith a frame-grabber daughter board 33 (FIG. 1) that interfaces with theultrasound probe 24 to obtain frame-by-frame image of the prostate glandas the probe is advanced. Preferably, a linear stepper motor is coupledto the probe 24 and to the automated motion control system 32 to allowthe image management software to control the movement of the probe. Inthis way, precise control of the frame-by-frame images used for thevolume study can be obtained and the dose plan generated as a result ofthe volume study can be correlated back to the frame-by-frame images.

Preferably, the probe 24 is operated in a similar manner at the time ofthe brachytherapy procedure and the frame-by-frame images of the volumestudy can be compared with the current images of the prostate gland. Amatching or registration of these two different sets of images can bedone manually or with the assistance of the computer processor 30. Oncethe matching is complete, the dose planning software can compare anychanges in the volume or positioning of the prostate gland and updatethe recommended dose plan accordingly. In this embodiment, as in thepreferred embodiment, the number and combination of radioisotope seedsand spacers preloaded into the cartridge 14 can be increased by a givenpercentage over the minimum number required by the predetermined doseplan to allow for changes to the dose plan as a result of changes to thevolume and position of the prostate gland that may occur between thetime of the volume study and the time of the brachytherapy procedure. Inthis embodiment, the physician would utilize the display 40 of theautomated system as the display for conducting the volume study andmonitoring the brachytherapy procedure, as well as for controlling theautomatic loading of the implant needles.

For a more detailed description of the operation of the user interface,reference is made to the co-pending application entitled “User Interfacefor a Radioisotope System” previously referenced.

Referring now to FIG. 14, an alternate embodiment of an automated system310 for loading low dose radioisotope seeds into a plurality of implantneedles is comprised of a loading station 12 into which a replaceablecartridge 314 may be positioned. It will be understood that thedescription of corresponding items in the automated system 310 issimilar to the preferred embodiment of the automated system 10 unlessotherwise noted. The cartridge 314 does not have any internal steppermotors, but rather interfaces a drive motor (not shown) in the loadingstation with a drive wheel 351 in the rotatable drum 354. The cartridge314 is held in place by a position registration mechanism 317 thatcomprises a ball and detent mechanism with the cartridge having at leastone detent defined on an outer surface and the loading station 12 havinga cam driven ball mechanism which selectively seats at least one ball inthe at least one detent to properly register the position the cartridge314 within the cartridge receiving structure 318.

An external push rod 362 is carried by a guide rail (not shown) and isdriven by a linear actuator (not shown) that is contained in the loadingstation 12, rather than in the cartridge 314. When the cartridge 314 isin position in the cartridge receiving structure 18, a first drive wheel351 preferably having a rubber ring 353 and a position encoder 366 inthe cartridge 314 are operably engaged by a second drive wheel (notshown) and a position sensor 364 in the loading station 12 to drive andsense the position of the rotatable drum 354 in the cartridge 314.

A position registration mechanism 317 preferably positions the cartridgewithin the cartridge receiving structure within the tolerance of+/−0.010 inches. Preferably, the position registration mechanism 317comprises a ball and detent mechanism with cartridge 314 having at leastone detent defined on our surface and loading station 12 having a camdriven ball mechanism that selectively seats at least one ball in theleast one detent to properly register the position of the cartridge 314within the cartridge receiving structure 18. The loading station alsoincludes at least one guide rail having a push rod 362 connected to alinear actuator that is controlled by the automated motion controlsystem 310 to selectively eject the radioisotope seeds and spacers fromthe periphery of the rotatable drum 354 of the cartridge 314.

In this embodiment, the encoder disc 366 for the rotatable drum 354 ispart of the cartridge 314, but the encoder circuitry and position sensor364 for the rotatable drum 354 and the encoder disc 366 and encodercircuitry 368 for the linear actuator 360 are part of the loadingstation 12. An EEPROM 339 that functions in a manner similar to theEEPROM 79 is part of the cartridge 314, although the design andinterface of this EEPROM 339 are configured such that it is easilyremoved from the cartridge 314 or is encased so as to allow thecartridge 314 to be sterilized without the need to disassemble parts ofthe cartridge 314. Thus, while there are more critical mechanicaltolerances that must be maintained in this embodiment, such as theinterface between the optical encoder disc 366 and the position sensor364, there are fewer electrical connections and less expense in thecartridge 314. In addition, disassembly of the cartridge 314 is notnecessarily required in order for the device to be sterilized.

In another alternate embodiment of an automated system 10 for loadinglow dose radioisotope seeds into a plurality of implant needles multiplereplaceable cartridges may be utilized in place of the singlereplaceable cartridge 14. For example, one cartridge could only containradioisotope seeds and another cartridge could contain material forspacers and plugs, although separate cartridges for each is alsocontemplated. Multiple cartridges may be configured like cartridge 14having internal stepper motors and circuitry, or may be configured likecartridge 314 having external stepper motors and circuitry. Theadvantage of multiple cartridges is that a smaller rotatable drum may beutilized for each cartridge, thereby increasing the indexing speed andthe separation of seeds and spacers into separate cartridges cansimplify the combinatorial arrangements of seeds and spacers.Preferably, the cartridges would be positioned in longitudinalsequential order relative to the path of travel of the push rod suchthat a seed and spacer are loaded together from the multiple cartridgeson a single pass of the push rod.

Alternatively, instead of providing individual spacers, one of thecartridges could supply a source of material from which the loadingstation creates spacers and/or plugs to be selectively ejected by theautomated motion control system into each of the needles. Because thespacers and plugs are made of relatively long lasting material such assuture or polymer material, this embodiment allows for a source of thematerial for the spacers or plugs to be supplied separately from supplyof the time critical radioisotope seeds. In the case of the spacers, forexample, it would be possible to provide a continuous coil of suturematerial as part of a replaceable cartridge with mechanisms to dispenseand cut the appropriate lengths of suture material as part of areplaceable cartridge or loading station. Alternatively, a replaceablecartridge or compartment in loading station may be loaded with a bulkquantity of plugs that are oriented and advanced into the properpositioning by mechanisms within the loading station.

In another alternate embodiment, the number of cartridges is made equalto the greatest number of radioisotope seeds to be loaded into a singleimplant needle such that all of the seeds and spacers for a singleneedle could be simultaneously loaded on a single pass of the push rod.In another alternate embodiment, multiple push rods could be used withthe multiple cartridges having multiple apertures to load multipleneedles at the same time.

It should be understood that in the broadest sense, the automated motioncontrol system of the present invention encompasses the various motors,actuators, encoders, detectors and feedback circuits that accomplish thecontrolled motion required to load the implant needles automatically andwithout manual intervention. It will be recognized by a person ofordinary skill in the art that numerous variations in the arrangement ofmotors, actuators, encoders, detectors and feedback circuits can be madeand still accomplish the function of loading the implant needlesautomatically, such as belt driven systems or screw-drive poweredsystems instead of direct motor driven systems, mechanical or electricalencoders and detectors instead of optical encoders and detectors, andlinear actuators instead of rotary actuators or vice versa.

Although the preferred embodiment of the automated system of the presentinvention has been described, it will be recognized that numerouschanges and variations can be made and that the scope of the presentinvention is intended to be defined by the claims.

1. An automated implantation system for implanting low dose radioisotopeseeds in a patient as part of a brachytherapy procedure comprising: astorage structure adapted to hold a plurality of radioisotope seeds; aneedle assembly; a Z-axis automated motion control system thatselectively moves at least the needle assembly along an insertion axisand into the patient and selectively ejects radioisotope seeds from thestorage structure into the needle assembly; an ultrasound probe; and acomputer processor operably connected to the Z-axis automated motioncontrol systems and to the ultrasound probe that captures and stores atleast one image from the ultrasound probe with the needle assembly inposition in the patient to selectively place at least one radioisotopeseed so as to form a record of the brachytherapy procedure.
 2. Theautomated implantation system of claim 1, wherein the implantationstation further comprises: an X-Y axis automated motion control systemthat selectively moves at least the needle assembly in a planeperpendicular to the insertion axis; and wherein the computer processorcaptures and stores an image from the ultrasound probe each time theneedle assembly is located at a different position in the planeperpendicular to the insertion axis by the X-Y axis automated motioncontrol system.
 3. The automated implantation system of claim 1, whereinthe computer processor captures and stores the at least one image fromthe ultrasound probe when the needle assembly is moved forward along theinsertion axis to a distal most location where radioisotope seeds willbe placed.
 4. The automated implantation system of claim 1, wherein thecomputer processor further includes a user interface that displaysinformation about the automated implantation system and accepts commandsfrom a user to control the process of implanting the plurality ofradioisotope seeds in the patient and wherein images from the ultrasoundprobe are displayed on the user interface in a separate window on theuser interface.
 5. An automated implantation system for implanting lowdose radioisotope seeds in a patient as part of a brachytherapyprocedure comprising: a seed cartridge having an aperture and containingat least a plurality of radioisotope seeds preloaded into the cartridge;a needle assembly; a Z-axis automated motion control system thatselectively moves at least the needle assembly along an insertion axisand into the patient and selectively ejects radioisotope seeds from theseed cartridge into the needle assembly; and a force sensor that sensesforces on the needle assembly along the insertion axis and is operablyconnected to at least the needle automated motion control system.
 6. Theautomated implantation system of claim 5, wherein the force sensorsenses whether the needle encounters resistance above an expected forcefor piercing tissue when the needle automated motion control systemadvances the needle assembly and, in response, the needle automatedmotion control system stops advancing the needle assembly.
 7. Theautomated implantation system of claim 6, wherein the needle automatedmotion control system is mounted in a compliant mount and the forcesensor is mounted at a rear of the needle automated motion controlsystem, the compliant mount providing with a minimum travel distance inthe event that the needle assembly encounters resistance above theexpected force for piercing tissue that forms a safety buffer to allowthe needle assembly to retract.
 8. The automated implantation system ofclaim 6, wherein the force sensor comprises a load cell mounted in acompliant mount at a rear of the needle assembly, the compliant mountproviding with a minimum travel distance in the event that the needleencounters resistance above the expected force for piercing tissue thatforms a safety buffer to allow the needle to retract.
 9. The automatedimplantation system of claim 5, wherein the force sensor senses whetherthe needle assembly has advanced into a non-tissue region and, inresponse, a user interface operably connected to the automated motioncontrol system provides an indication to a user that the needle assemblyhas advanced into the non-tissue region.
 10. A method of operating anautomated implantation system for implanting low dose radioisotope seedsin a patient as part of a brachytherapy procedure comprising: (a) usingan ultrasound probe to establish a base plane for a position of an organbeing treated in the brachytherapy procedure; (b) using the automatedimplantation system to implant low dose radioisotope seeds in thepatient with at least a Z-axis automated motion control system thatimplants radioisotope seeds to a depth determined in relation to thebase plane; (c) monitoring the position of the organ during step (b);and (d) automatically adjusting the base plane used in step (b) inresponse to any movement in the position of the organ during thebrachytherapy procedure.
 11. A method of operating an automatedimplantation system having a Z-axis automated motion control system andan X-Y axis automated motion control system that control at least aneedle assembly for implanting low dose radioisotope seeds in a patientas part of a brachytherapy procedure comprising: (a) providing anultrasound probe to establish a base plane for a position of an organbeing treated in the brachytherapy procedure; (b) using the automatedimplantation system to implant low dose radioisotope seeds in thepatient with the Z-axis automated motion control system implantingradioisotope seeds along an insertion axis generally perpendicular tothe base plane and the X-Y automated motion control system moving theinsertion axis in the base plane; (c) automatically capturing andstoring at least one image from the ultrasound probe for each uniqueposition of the insertion axis in the base plane so as to form a recordof the brachytherapy procedure.